A sealed glass phial containing 25 grams of “heavy water” from Norsk Hydro, similar to what was targeted for destruction in the Special Operations Executive’s Operations Grouse, Freshman and Gunnerside. Photo by SSPL/Getty Images

The exploits of the Special Operations Executive are the stuff of legend. This episode continues to look at a few of the group's missions, and what became of the SOE after WWII.